Process for reducing tendency of wool to felt



United States Patent 3,236,585 PROCESS FOR REDUCING TENDENCY 0F WOOL T0 FELT Louis Chesner, Luton, Ronald Preston, Dunstable, and John Leonard Raynes, Belper, England, assignors to Precision Processes (Textiles) Limited, Ambergate, Derbyshire, England, a British company No Drawing. Filed Sept. 5, 1962, Ser. No. 221,416 13 Claims. (Cl. 8127.6)

The present invention relates to the treatment of wool to reduce its tendency to felt during washing or cleaning.

The term wool as used herein means sheeps wool and other animal fibres capable of being felted, and also wool in any form and materials containing or consisting of wool. Examples of forms of wool are loose fibres, slubbing, tops, roving, yarn, knitted or woven fabric, or garments.

The present invention provides a process for reducing the tendency of wool to felt which comprises treating wool under aqueous conditions with (a) at least one N-chloro compound selected from trichloroisocyanuric acid, dichloroisocyanuric acid and salts of the latter which are at least sparingly soluble in water and (b) at least one peroxy acid or a salt thereof which is at least sparingly soluble in water, at least the treatment with said peroxy acid or salt thereof being carried out under acid conditions.

The N-chloro compound reduces the tendency of the wool to felt. The peroxy acid or salt thereof may, but does not necessarily, reduce the tendency of the Wool to felt. It has surprisingly now been found that the use of the two reagents produces a greater shrink resistance than either used alone and the resulting products have a better colour than that obtained When the N-chloro compound or compounds is used alone to treat the wool.

The present process does not contemplate the use of markedly alkaline reacting baths. However, certain waters used in textile processing have a slight natural alkalinity (pH up to about 8.2) and at the concentrations used to treat wool the aqueous solution of the N-chloro compound (which per se is either neutral or acid in reaction when dissolved in distilled water) may have a mildly alkaline reaction. It is not necessary to remove this mild natural alkalinity since it has been found that the wool itself will quickly correct this condition.

The rate of treatment of the wool can be controlled either by varying the temperature or varying the pH value or both. The treatment with the peroxy acid or salt thereof is, however, always carried out under acid conditions and so is at least a part of the treatment with the N-chloro compound. The rate of treatment of the wool can be increased by increasing the temperature and/0r lowering the pH value of the bath or baths employed,

and vice versa.

It is preferred that the treatment with both said N-chloro compound and with said peroxy compound or salt thereof is wholly carried out under acid conditions. In this way the process can very conveniently be conducted at room temperatures and, if desired, in a single bath. At above 30 C. single bath acid treatments may be unduly rapid in their action and unless the concentration of N-chloro compound is sufficiently low give rise to uneven treatment of the wool. A long liquor ratio is desirable in such cases. When a single bath is used containing both reagents it is preferred that it be initially at a pH within the range of 3 to 6.

It has been found that under acid conditions of operation using suitable concentrations of N-chloro compound and peroxy acid or salt thereof in a single bath the rate of exhaustion of the N-chloro compound is much more rapid than the rate of exhaustion of the peroxy compound. In a continuous process, therefore, steps must be taken to replenish the N-chloro compound at a much greater rate than the peroxy compound. Whilst this is quite feasible there are advantages in carrying out the treatment in two separate baths.

Accordingly, in a preferred feature of the invention the treatment with said N-chloro compound and with said peroxy compound is carried out sequentially.

In carrying out such a process the Wool may first be treated with a peroxy acid or a salt thereof under acid conditions and then with the N-chloro compound. In sequential treatments the treatment with the N-chloro compound or compounds can be conducted in acid, neutral or initially mildly alkaline conditions. As in single bath treatments, acid pH values in both baths are much preferred. The pH value of the bath containing the peroxy compound may be between 0.5 and 5.0, preferably between 1 and 4.0, whilst that of the bath containing the N-chloro compound may be between 5.5 and 7.0, preferably between 6.0 and 6.9 when measured in distilled water. Using mildly alkaline waters the pH of the bath containing the N-chloro compound may initially be 8.1 to 6.0. Temperatures up to 30 C. are also preferred. At temperatures above this, e.g., up to 60 C., treatment employing initially mildly alkaline conditions in the bath containing the N-chloro compound may be advantageous. A sequential treatment is preferably carried out in separate baths but can, if desired, be carried out in the same bath by adding the second treating agent at a suitable time after adding the first. The use of separate baths enables treatment to be carried on continuously as it is then relatively easy to maintain the correct concentrations of each reagent in the appropriate bath.

To secure adequate processing in a reasonable time the temperature of all baths should be at least 5 C.

In carrying out the sequential treatment of wool first with a solution of a peroxy acid or salt thereof under acid conditions and then with an N-chloro compound, the treated material emerging from the bath of peroxy acid or salt thereof is preferably subject to processing which will reduce its acid content. This may be effected by passage through a mangle which has been adjusted to control the take-up of treating liquor to a predetermined amount such as or of the weight of the Wool. Alternatively, or in addition, it may be passed through an intermediate bath of water containing a wetting agent and then through a mangle. Such intermediate treatments enable the pH value of the bath containing the N-chloro compound to be more closely controlled as well as maintained on the acid side. If a sequential treatment is carried out with the baths in the reverse order it is preferred to use a mangle to control the take-up of the bath containing the N-chloro compound. In continuous processing control of take-up of liquor and addition of further treating agent should be correlated.

When a salt of dichloroisocyanuric acid is employed the sodium salt is preferred. However, other alkali and alkaline earth metal salts such as the potassium, calcium or barium salts may be used if desired. The quantity of N-chloro compound employed in a single bath treatment is desirably such as to give from 1.4% to 2.5% of available chlorine based on the weight of the wool. In continuous processing employing countercurrent movement of wool through a bath of reagent which is being replenished at one end much higher concentrations are permissible at that end, e.g., 2.5% of available chlorine, provided that the time of contact therewith is correspondingly reduced.

The use of a peroxy acid or salt ensures that the treated product has a better (whiter) colour than that obtained when the N-chloro compound is used alone. When treatment with the peroxy compound is employed in conjunction With the sequential or simultaneous treatment with the N-chloro compound, the degree of resistance to felting imparted to the Wool is also greater than that obtained when either compound is used alone. The effect is greater than the sum of the combined effects and is an unexpected example of synergism. This is illustrated in EX- ample 9.

The preferred peroxy compounds are peracetic acid, permonosulphuric acid and the alkali metal salts of the latter, especially potassium permonosulphate. The peroxy compound may be formed in situ when sequential treatments are being given; thus, peracetic acid, performic acid and the at least sparingly Water soluble metal salts of these acids may be produced in this Way. Since such formation in situ must be carried out in the absence of the N- chloro compound this procedure is not recommended in carrying out a single bath process. This is because the hydrogen peroxide essential to the production thereof reacts with the available chlorine of the N-chloro compound and there will thus be mutual destruction of the materials essential for the treatment.

It is essential in processes in accordance with the present invention to employ true peroxy compounds, that is to say, true peracids and salts thereof. Thus, the alkali metal perborates cannot be employed since they are not the salt of true peracids: in aqueous solution they dissociate to form the corresponding alkali metal borate and hydrogen peroxide, which latter is then available to react with the N-chloro compound employed in the manner referred to in the previous paragraph. This point is further illustrated by Example 8.

In order to secure uniformity of treatment the wool should either first be wet out in an aqueous bath containing a wetting agent or such a material should be included in the bath or baths in which the treatment in accordance with the invention is carried out.

After the treatment it is desirable to subject the wool to a treatment which will remove residual chlorine and/ or peroxy compound. Suitable reagents for this purpose are sodium sulphite, sodium bisulphite and hydrogen peroxide.

The advantages of the process according to the present invention as compared with prior processes are that it imparts to Wool an excellent resistance to felting in addition to a good handle and colour. Because of the controlled and uniform manner of release of the available chlorine, such wool is capable of being dyed in a level manner and, because of its good colour, under substantially the same conditions and with the same dyestuffs that are in use for wool which has been subjected to shrink resistance treatment with permonosulphuric acid and its salts at low pH values.

The following examples illustrate the invention. The amounts of the materials are measured in parts by weight. Unless otherwise stated, the Washing test employed in the examples is the standard washing test set out in British Standard Specification No. 1955: 1953. In all the examples in which the test was employed, similar tests were carried out on both the untreated fabric and the fabric after treatment.

Example 1 20 parts of an all Wool knitted fabric of 56s quality, which had been previously wetted out, were treated in a bath containing 600 parts of water, 0.5 part of sodium dichloroisocyanurate (this quantity yields 1.5% of available chlorine), 0.15 part of peracetic acid (calculated as and 0.02 part of a proprietory wetting agent for 30 minutes at 18 C. The'pH value of the solution was 4.3. 1 part of sodium bisulphite was then added and treatment continued for a further 30 minutes. The fabric Was then well rinsed in water.

The resultant fabric possessed a good handle and colour, and the standard Washing test gave the following result:

Percentage area State of wool: felting shrinkage Untreated 50.8 Treated 2.1

Example 2 20 parts of an all wool knitted fabric of 64s quality, which had been previously wetted out, were treated in a bath containing 0.5 part of sodium dichloroisocyanurate,

Percentage area felting shrinkage Untreated 52.6 Treated 9.6

The above process was repeated using 0.49 part of calcium dichloroisocyanurate in place of the sodium dichloroisocyanurate. Similar results were obtained.

State of wool:

Example 3 30 parts of wool yarn of 56s quality, which had been previously wetted out, were treated at 18 C. and a pH value of 6 for 30 minutes in 1000 parts of water containing 0.75 parts of dichloroisocyanuric acid (this quantity yields 1.5% available chlorine), 0.3 part of potassium permonosulphate and 0.03 part of a proprietory wetting agent. 1.5 parts of sodium bisulphite were added and treatment continued for a further 30 minutes. The wool yarn was finally Well rinsed in water.

The handle and colour of the treated yarn was satisfactory, and a hand-milling test showed the treated yarn possessed good shrink-resistance when compared with the original yarn.

Example 4 30 parts of an all-wool knitted fabric of 56s quality, which had previously been wetted out, were treated at 18 C. and a pH value of 5.2 in 1000 parts of water containing 0.52 part of trichloroisocyanuric acid (this quantity yields 1.5% available chlorine), 0.3 part of potassium permonosulphate and 0.03 part of a proprietory wetting agent. After 30 minutes, 1.5 parts of sodium bisulphite were added and treatment continued for a further 30 minutes, when the fabric was well rinsed with water.

The handle and colour of the treated fabric was good, and the standard washing test gave the following result:

Percentage area State of wool: felting shrinkage Untreated 50.6

Treated 7.2

Example 5 1 part of a solid blend containing 0.5 part of the sodium salt of dichlorocyanuric acid and 0.17 part of potas- Percentage area felting shrinkage 48.6 8.1

State of wool:

Untreated Treated Example 6 Three samples of an all wool knitted fabric of 64s quality were taken. Two of these were each divided into two parts viz. a, b; c, d. Parts a, b, c and d were subjected at 18 C. to a 30 minute treatment with a bath identical with that used in Example 2 employing the same liquor ratio. Samples a and were then treated with a 5% aqueous solution of sodium bisulphitc for 30 minutes and samples b and d with a 2.5% aqueous solution of 100 volume hydrogen peroxide for the same period.

All four treated parts, and the untreated sample, were then washed and gave the following results:

Percent area Samples After treatment felting Reflectance shrinkage of product (average) Sodium bisulphite 13. O 71 b, d Hydrogen peroxide 26. 3 66 Untreated eontro 49. 6 64 Example 7 This example illustrates a separate bath treatment at 18 C. in which samples of wool were treated first in a bath containing aqueous peracetic acid, squeezed, and then, without washing, in a bath containing aqueous sodium dichloroisocyanurate. Each sample was then subjected to a 15 minute treatment in a 5% aqueous solution of sodium bisulphite. Thereafter all the samples were washed at 50 C., this being a much more severe test than the standard 30 C. test. The following results were obtained:

Sodium salt bath Percent peracetic Time of each Percent area acid (calculated as treatment, ltmg 100%) Percent Imus. shrinkage available pH chlorine 1 1 Derived from the sodium dichloroisocyanurate used.

Example 8 6 then submitted to shrink resistance tests. The results were as follows:

Treating bath 5 Percent Percent Test available area felting Percent peroxy compound chlorine pH of shrinkage om sodium bath dichloroisocyanurate 10 (a).. 0.75% peracetic acid (0111- None 55. 7

culated as 100%). (b). None 1.5 so 11.8 (c) 0.75% peracetic acid 1. 5 4. 4 1. 9 (d) 1.22% hydrogen peroxide 1. 5 5. O 38.0 (100 vol.).

(e) Untreated control 51.6 (f) Potassium permonosul- None 48.4

phate to give 0.75% per monosulphuric acid (calculated as 100%). (g) None 1.5 0.0 11.8 11)"--- As (1') 1.5 4.2 4.2 (1). Sodlum perborate to give 1. 5 5.0 38.0

equivalent hydrogen peroxide as (d). (3').-- Untreated control 51.6

A comparison of the results of test (0) with those of tests (a) and ([1) reveals the remarkable effect of using peracetic acid and sodium dichloroisocyanurate in the same bath. Treatment with peracetic acid alone under the particular conditions used actually reduced the resistance to shrinkage but when this treatment was combined with a treatment with sodium dichloroisocyanurate a greater resistance to shrinkage was obtained than when the dichloroisocyanurate was used alone. A similar comparison may be made between the results of test (It) and 3 tests (7) and (g). When hydrogen peroxide or sodium borate and sodium dichloroisocyanurate are used together in one bath-tests (d) and (i)--the results are poor.

Example 9 To show the relative rate of utilisation of permonosulphuric acid and sodium dichloroisocyanurate when present in the same bath the following trial was run.

A first bath, maintained at 23 C., was made up containing per litre: 2 gms. of permonosulphuric acid, 6 gms. of sodium dichloroisocyanurate and 5 gms. of a proprietory wetting agent, the whole being adjusted to pH 4 by the addition of aqueous 10% caustic soda solution.

A second bath, maintained at 25 C. consisted of a 10% by weight aqueous solution of sodium sulphite.

Using a liquor ratio of 20:1 (i.e., weight of bath to weight of fabric of 20:1) three samples of wool serge were, in turn, treated in the first bath, passed through a mangle adjusted to secure a liquor take-up of 75% of the weight of the fabric, then into the second bath and finally rinsed in water. The dry weights of the three samples before treatment were 270 gms., 220 gms. and gms. respectively. The time of immersion in the first bath was 30 seconds for each sample. Samples of each bath were taken for estimation of residual chemicals.

Throughout the pH value of the bath remained between 3.9 and 4.0. It will be seen that the rate of removal of sodium dichloroisocyanurate was approximately five times that of the permonosulphuric acid when both were present in the same bath.

Example 9 was repeated using a first bath containing per litre: 4 gms. o-f permonosulphuric acid, 3 gms. of sodium dichloroisocyanurate and gms. of a proprietory 8 gms. of a proprietory wetting agent whilst a third bath consisted of a aqueous solution of sodium sulphite crystals.

For the subsequent tests the concentrations of the Wetting agent, the PH Value being adjusted to 4 as in 5 active chemicals in the first and second baths were as Example 9. In this case the percentage loss in strength Set out 111 the pp table, the amount of Wfittillg of each chemical was found to be; agent being unchanged, and [1116 third bath being the same in all cases. Permonosulphuric Sodium dichlorolso- The samples were in the first and second baths for percent cyanurate' Percent 10 seconds each. From the first bath the serge was passed F. t 1 5 7 26 through a mangle adjusted to secure a liquor take-up of fii f gggiglfjj 1 31 75% of the weight of the fabric and then into the sec- Third sample. 8 29 0nd bath.

Average 5.0 28.7 15 The products, after drying, were evaluated for colour and samples were submitted to the shrink resistance test Throughout the pH value of the bath remained between for 60 minutes nad the solubility in alkali determined.

Permonosulphurlc acid bath Sodium dichlorolsocyanurate bath Ref. Gone. in Titre pH Gone. in Titre pH Colour gms/lltre gmsJlltre Before After Before After Before After Before After 3 5.3 3.4 1.1 1.2 2 3.1 2.0 3.1 4.0 Excellent. 2 3.5 2.4 1.1 1.5 2 3.1 2.0 8.0 4.3 Better than untreated. 2 3.5 2.3 1.1 1.6 4 6.2 4.9 7.3 4.7 Do. 2 3 5 2.4 1.1 1.6 6 9.4 7.4 7.0 4.9 Do. 2 3. 5 2. 4 1. 1 1. 6 Excellent. 3 5.3 3.3 1.1 1.2 Do.

2 3.1 2.3 8 1 6.6 Distinctly yellow. 4 6.2 5.4 7.8 6.2 Do. I 6 9.4 6.2 7.0 5.9 Do.

3.95 and 3.8. In this case the average rate of removal It will be understood that in the fir t four trial th of sodium d-ichloroisocyanurate was more than 5.6 times and remaining in the fabric after passing through the the rate of removal of the permonosulphuric acid. mangle served to acldify the sodium dichloroisocyanurate. Shrink testing was carried out upon samples of the The pH values recorded under before are before such products of Examples 9 and 10 and also upon (a) a passage and are due to a slight natural alkalinity in the control sample and (b) a sample treated as described water used. The last five trials are for comparative purin Example 9 but omitting the permonosulphuric acid poses. These results show that treatment in a dilute from the first bath. In each case samples were submitted solution of permonosulphuric acid followed by treatto 30-minute and 60-minute washing tests. The followment in a dilute acidified sodium dichloroisocyanurate ing results were obtained: solution gives a fabric having a better colour than that 5 obtained by treatment with the same concentration of sodium dichloroisocyanurate alone. Area shrinkagerpement The shrink resistance and alkali solubilities were as follows: 30 minute wash. 60 minute wash.

35.3 61.4 g 12:; R f (30 rglinuteshwaihing Perclergglalkali ermonosul huric acid. e 8S areas Ill'l age, S0 U. 11 y Ez ample 10- 5. 6 10. 8 Percent Permonosulphuric acid at 16. 4 4

PH 61 10. a 1.6 21.3 3.9 17.9 It will be seen that sodium dichloroisocyanurate alone k2 lgji produces a resistance to shrinkage markedly lower than g g that of the two compounds when used together and when 1 it is initially present in the same concentration and 61 13.1

This resistance is is used under the same conditions. also lower than that obtained with other concentrations of the two reagents when used together. Under such mildly acid conditions permonosulphuric acid alone gives but poor results but these are much improved by the use of mixtures.

Example 11 In another series of tests wool serge was first treated in a bath containing permonosulphuric acid and then in a bath containing sodium dichloroisocyanurate.

For the first test a first bath was made up containing per litre: 3 gms. of permonosulphuric acid and 5 grns. of a proprietory wetting agent. A second bath contained per litre 2 gms. of sodium dichloroisocyanurate and 5 The area shrinkage in tests A, B, C and D is very satisfactory notwithstanding the severity of the treatment. The sodium dichloroisocyanurate alone did not give a perceptible reduction in area shrinkage when used alone although the titre values clearly establish that some reaction took place and there was a fall in the pH value of the bath. The two reagents can be used in turn, however, to give a product of very satisfactory colour and with a very small shrinkage on prolonged washing.

A sample produced in accordance with Ref. C before and after washing was submitted to dry bursting strength tests on the Mullen tester. The following results were obtained (average of 10 samples):

Dry bursting strength, lbs./in.

10 ous bath at a temperature within the range 560 C. with (a) at least one N-chloro compound selected from the group consisting of trichloroisocyanuric acid, dichloroisocyanuric acid and salts of dichloroisocyanuric acid fig a 55 5333 25 which are at least sparingly soluble in water and with C after 'g 98 (b) a peroxygen compound selected from the group coni sisting of peroxy acids and salts of peroxy acids which These results are clearly satisfactory. are at least sparingly soluble in water, said bath initially Example 12 having a pH within the range of 3-6.

5. The process according to claim 4 in which the tem- The procedure outlined in Example 11 was repeated perature of said bath does not exceed C. but the order of application of the baths was reversed. 6. A process for reducing the tendency of wool to The following results were obtained felt which comprises the steps of first treating wool at a Sodium dichloroisocyanurate bath Permonosulphuric acid bath Ref. Gone. in Titre pH Gone. in Titre pH gmsJlitre gmsJlitre Before After Before After Before After Before After 2 a. 1 2. 75 8.1 6 2 2 a. 1 2.65 1.1 1.4 K 4 5.2 5. 7.8 5 9 2 3.6 2. 95 1.1 1.4 L 6 9.4 5.8 6.9 5 7 2 3.55 3.1 1.1 1.3 2 3. 55 2. 5 1.1 1. 2

The shrink resistance and alkali solubilities were as temperature of from 5 C. to 60 C. in an aqueous bath follows: containing at least one peroxygen compound selected from the group consisting of peroxy acids and salts of h P E 1k 1 peroxy acids which are at least sparingly soluble in water, 60 minutes W s 211 35 said treatment being carried out under acid H congg igg mummy ditions, and thereafter further treating the thug treated wool at a temperature of from 5 C. to 60 C. in a second 56 10.2 aqueous bath containing at least one N-chloro compound 2-2 ig-g selected from the group consisting of trichloroisocyanuric 3:4 16:1 40 acid, diChlOrOisOcyanuric acid and metal salts of dichloroisocyanuric acid which are at least sparingly soluble in water, at least a part of said treatment with said N-chloro compound being carried out under acid pH con- The area shrinkage figures for tests I, K and L are ditions. more satisfactory than those for permonosulphuric acid 7. The process of claim 6 wherein the treatment with alone. Sodium dichloroisocyanurate is a substantially said per-oxygen compound is carried out at a pH of from neutral salt and it is clear that the slight natural alkalinity about 0.5 to about 5.0 and the treatment with said N- of the water used for the bath quickly disappears and chloro compound takes place at an initial pH in the the bath readily changes over to a mild acidity in the range of from about 5.5 to about 8.1. presence of wool and in the absence of any added alkali. 8. The process according to claim 6 in which the Further tests showed that dichloroisocyanurate carried peroxy acid is permonosulphuric acid. over int the perrnonosulphuric acid bath quickly dis- 9. The process according to claim 8 in which the N- appeared at the lower pH prevailing therein and it could chloro compound is an alkali metal salt of dichloroisonot be detected after the fabric had been removed therecyanuric acid. from. The colour of the treated goods was satisfactory 10. A process for reducing the tendency of Wool to in all cases. felt which comprises the steps of first treating wool at a What is claimed is: temperature of 5 to C. in an aqueous bath contain- 1. A process for reducing the tendency of wool to felt ing t l a t one N- h1 compound l t d fr h which comprises treating wool under aqueous conditions group i ti f t i hl i i id dichlorgisgand at a temperature within the range 560 C. with (a) cyanuric acid and metal salts of dichloroisocyanuric acid at least one N-ohloro Comp und sfilected from the group 60 which are at least sparingly soluble in water and thereconsisting of trichloroisocyanuric acid, dichloroisoafter further treating the thus treated wool at a temperacyanuric acid and salts of dichloroisocyanuric acid which ture of 5 C. to 60 C. in a second aqueous bath containare at least sparingly soluble in Water and with a ing at least one peroxygen compound selected from the peroxygen compound selected from the group consisting group consisting of peroxy acids and salts of peroxy acids of peroxy acids and salts of perxoy acids which are at which are at least sparingly soluble in water, at least said least sparingly soluble in water, at least part of th treatment with a peroxygen compound being carried out treatment with (a) and the treatment with (b) being under id H di i carried out under acid conditions. 11. The process of claim 10 wherein the treatment with 2. The process as claimed in Claim 1 n Which treatsaid N-chloro compound is carried out at an initial pH in ment with and With is Substantially Wholly 7 the range of from about 5.5 to about 8.1 and the treatcarried out under acid conditions. ment with said peroxygen compound is carried out at 3. Wool having a reduced tendency to felt which has a pH of from about 0.5 to about 5.0. been produced by the process of claim 1. 12. The process according to claim 10 in which the 4. A process for reducing the tendency of wool to felt N-chloro compound is an alkali metal salt of dichlorowhich comprises simultaneously treating wool in an aqueisocyanuric acid.

3,236,585 11 12 13. The process according to claim 12 in which the 3,106,440 10/ 1963 Lewin 8109 X. peroxy acid is permonosulphuric acid. 3,144,300 8/ 1964 Cosnard et a1 8127.6

References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 5 219,930 1/ 1959 Australia.

2,993,747 7/1961 Scott 8-127.6 3,071 431 1/1963 Mertens et a1. NORMAN G. TORCHIN, Przmary Exammer. 3,097,913 7/1963 Bergen et a1. 8128 

1. A PROCESS FOR REDUCING THE TENDENCY OF WOOL TO FELT WHICH COMPRISES TREATING WOOL UNDER AQUEOUS CONDITIONS AND AT TEMPERATURE WITHIN THE RANGE 5-60*C. WITH (A) AT LEAST ONE N-CHLORO COMPOUND SELECTED FROM THE GROUP CONSISTING OF TRICHLOROISOCYANURIC ACID, DICHLOROISOCYANURIC ACID AND SALTS OF DICHLOROISOCYANURIC ACID WHICH ARE AT LEAST SPARINGLY SOLUBLE IN WATER AND WITH (B) A PEROXYGEN COMPOUND SELECTED FROM THE GROUP CONSISTING OF PEROXY ACIDS AND SALTS OF PERXOY ACIDS WHICH ARE AT LEAST SPARINGLY SOLUBLE IN WATER, AT LEAST PART OF THE TREATMENT WITH (A) AND THE TREATMENT WITH (B) BEING CARRIED OUT UNDER ACID CONDITIONS. 